Graphic representations of large size engineering models, medical images, or computer generated scenes for multimedia applications typically contain millions of facets, that is, elements of surface tesselations. The computing power required for rendering such complex models, in realtime, is presently beyond the reach of parallel data processing architectures. However, realtime interactive manipulation of viewing conditions provide important clues for understanding an object's geometry and relative positions. In general, these visual clues cannot be obtained from sequences of static images. Furthermore, interactive viewpoint manipulation to accomplish, by example, a walkthrough through an engineering assembly model, or to visually inspect medical data, requires realtime feedback and smooth object motion.
To achieve the required performance, it is known to use an alternate representation of the model, which is less computationally expensive to display. For example, in many Computer Assisted Design (CAD) and animation systems wireframe models, or boxes placed around the objects, are used during realtime manipulation. However, these simplified graphic substitute models often produce images having thousands of displayed lines. This number of lines is difficult to interpret, especially in clustered visual environments.
It is thus one object of the invention to provide method and apparatus that employs one or more simplified object models for display to a viewer, the simplified models being stored and accessed as required.
It is another object of the invention to provide a method for simplifying a triangulated object model, the method operating on vertices of the model.